Tap changing transformer



Nov. 7, 1933. L... H. HILL TAP CHANGING TRANSFORMER 7 Filed Nov. 27. 1951 0/1 LEVE L of the transformer tank. This mechanism comprises a stuffing box 29 which is attached to the side wall 5. A rod 30 extends through stufiing box 29. Oil from the interior of the tank is prevented from leaking through the stufling box by means of packing 31 and a packing nut 32. To the inner end of rod 30 is attached "a forked crank member 33 having a slot in the end thereof adapted to receive pin 27. To the other end of rod 30 is attached an operating handle 34 which is provided with a locking mechanism which comprises an arm in which spring pressed looking pin 35 is located. Locking pin 35 is adapted to engage holes in indicator plate 36 which is attached to transformer wall 5. The outer end of locking pin 35 is provided with a pull ring 37 and a hole- 38 which is so alined with holes in the arm of the operating handle 34 that the hasp of a padlock may be inserted therethrough.

Referring now to Figure 2, it is seen that the indicator plate 36 is provided with a plurality of holes arranged on the arc of a circle and adapted to receive locking pin 35. These holes, which are marked by indicating numerals A to H, inclusive, determine and indicate the position in which respective contracts of the switch mechanism are maintained during operation of the transformer. Obviously a fewer or greater number of contacts than shown may be arranged in the arc of a circle depending upon the number of adjustments desired. It is to be noted that this figure also shows the mannerin which pin 27 cooperates with forked crank member 33.

Figure 3 shows more in detail the arrangement of stationary and movable contacts noting that the rotary contact assembly 23 comprises a hub member 39 and two pairs of contacts 40, 40 and 41, 41' attached thereto. Each of these contacts consists of a pair of bifurcated spring biased contact members 40, 40. and 41, 41' adapted to wipe two sides of the flat portions 19' of contact members 19. Contacts .27, 40' and 41, 41 are all electrically connected -by hub member 39. It is to be understood that other forms of rotary switches may be used in place of the form shown without departing from the spirit of this invention.

In operating the, above described mechanism it is necessary first to deenergize the transformer, then unlock the pull ring 3'7, disengage locking pin 35 from one of the holes in plate 36 by pulling ring 37, and then move the switch to the desired position noting that the locking pin will snap into the selected hole when the desired position is reached. Although the drawin shows but two sets of panels with contacts thereon, it is to be understood that a greater number of switch units may be operated from the same insulating shaft, noting for example, that in a three-phase transformer three or six switch units will be used, depending upon the manner in which the taps aremade.

Should it be desired to untank the transformer it is only necessary to move the operating handle to position A in which the forked lever 33 extends vertically upward. Then the cover clamps may be removed and the transformer untanked by hoisting the cover and the core and coil assembly and the switch mechanism mounted thereon. It is to be understood that if the core and coil assembly is not attached to the cover 6,

that the cover may first be removed and then the coil and core assembly together with the tap-changing mechanism attached thereto may be hoisted from the tank. In assembling the device it is only necessary to aline the pin 27 with the slot in lever 33 so that when the transformer core and coil assembly is lowered into the casing an operating connection will be established between the switch operating mechanism and the tap-changing mechanism.

It is to be understood that the disclosure herein described is merely illustrative of the invention and is not to be taken in a limiting sense, changes in details of construction and arrangement of parts being permissible so long as within the spirit of the invention and the scope of the claims which follow.

It is claimed and desired to secure by Letters Patent:

1. In combination, a transformer casing having a removable cover, a core and coil assembly mounted within said casing and attached to said cover, a tap-changing mechanism attached to said core and coil assembly, a body of liquid covering said core and coil assembly and said tap-changing mechanism, a horizontally disposed insulating shaft for operating said mechanism, a metal shaft extending horizontally through said casing below the level of said body of liquid, a stumng-box for said metal shaft, a disconnectible connection between said metal shaft and said insulating shaft whereby said cover, said core and coil assembly and said tapchanging mechanism may be removed from said casing as a unit, a handle connected to said metal shaft, and means for locking said handle in any one of a plurlity of positions.

2. In combination, a transformer casing, a body of liquid within said casing, a core and winding assembly immersed in said body of liquid, a rotary tap-changing switch attached to said core and winding assembly and immersed in said liquid, a stuffing box attached to said casing, a shaft extending horizontally through said stuffing box for operating said switch, an indicating plate surrounding said stuffing box and having a plurality of holes therein, a handle attached to said operating rod, a spring biased plunger carried by said handle and adapted to pass into said holes so as to retain said handle in any one of a plurality of positions, and a pin and fork connection between said shaft and said tap-changing switch whereby said tap-changer switch and said core and winding assembly may be removed as a unit when said handle is retained in one of said plurality of positions.

3. A transformer comprising a casing having a side wall and a removable cover, a core and winding assembly arranged within said casing and attached to said cover so as to be removable therewith, a tap-changing switch mounted on said core and winding assembly and having a plurality of stationary contacts connected to various turns of said winding, said switch also having a rotary contact actuating member horizontally mounted on said coil and winding assembly, manually operable mechanism mounted on the outside of said side wall and having an operating shaft extending through said side wall coaxial with said contact actuating member, and a pin and fork connection connecting said operating shaft and said actuating member so that said cover, said tap-changing switch and said core and winding assembly may be removed from the side wall of said casing independent of said manually operable mechanism.

4. A transformer comprising a casing havof the said side wall and including an operating shaft extending through said side wall, and means for drivingly connecting said rotary contact actuating shaft with said operating shaft, said connectingmeans being so constructed as to cause the automatic disconnection thereof upon the removal of said core and coil assembly and said tap-changing switch as a unit when said tap-changer operating mechanism is in a predetermined, position.

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